It’s as easy as

brew install vagrant

Ha! Nice try there, buddy:

Error: No available formula with the name "vagrant" 
==> Searching for similarly named formulae...
Error: No similarly named formulae found.
==> Searching taps...
These formulae were found in taps:
homebrew/completions/vagrant-completion  Caskroom/cask/vagrant-manager
Caskroom/cask/vagrant-bar                Caskroom/cask/vagrant
To install one of them, run (for example):
  brew install homebrew/completions/vagrant-completion

According to this discussion, it’s not allowed by homebrew but the homebrew-cask project enables users to install vagrant.  (So *that’s* why I couldn’t get Chrome, Dropbox, 1Password, VLC and other apps installed view homebrew – there’s some rule or constraint in homebrew that only enables non-GUI apps.)

So let’s install the Cask tools – this article makes me feel silly even – you just have to know to use the “cask” keyword, as in:

brew cask install vagrant

Thus do I get vagrant v1.9.1 in one (slightly unexpected) command line.  (And don’t forget virtualbox and vagrant-manager!)

Which is super-cool, because many package managers end up with non-current builds of the tools in their catalogs.

And as a bonus, they mention a bunch of quicklook plugins that I never even thought to go looking for – markdown, syntax-highlighted code,  JSON, CSV and more!